Specifications

SDM-100A Satellite Modem Theory of Operation
Rev. 0 4–25
Two fault outputs are provided on dry contact Form-C relays on the Demodulator/M&C
card, and are sent to the interface card. The signals are buffered and output for use in
monitoring fault status, and are available on the FAULT connector on the modem rear
panel. These are:
• MODULATOR faults
• DEMODULATOR faults
Generation of these fault conditions is described in Chapter 3.
4.4.3.2 Connector Pinouts
The RS-232-C interface is provided on a 25-pin D female connector (DCE) accessible
from the rear panel of the modem. Screw locks are provided for mechanical security of
the mating connector.
Signal Function Name Pin #
Ground GND 1, 7
Send Data SD 2
Receive Data RD 3
Request To Send RTS 4 (See note below)
Clear To Send CTS 5 (See note below)
Data Mode DM 6
Receiver Ready RR 8
Master Clock MC 9
Demod Fault DF 11
Send Timing ST 15
Receive Timing RT 17
Terminal Timing TT 24
Mod Fault MF 25
No Connection 10, 12, 14, 16, 19, 20, 21, 22, 23
Note: The Request to Send (RTS) line is normally hard-wired to the Clear to Send
(CTS) line by JP11, pins 5 and 6, on the Demodulator/M&C card (AS/4973).